Many propulsion and transmission systems are known in the prior art for use with bicycles and other manually-powered cycles such as exercycles. Most commonly, the cycle is propelled or operated by foot pedals which are connected through suitable transmission means to one or more of the cycle wheels, the pedals rotating about a central axis passing through the cycle frame along a circular path of movement about the axis when pumped by the rider.
My U.S. Pat. No. 5,496,051, issued Mar. 5, 1996, discloses apparatus for propelling a manually-powered cycle including first and second pedals which move along spaced, linear paths of movement. The pedals are connected to the drive wheel of the cycle through a power train including elongated flexible transmission elements which wrap about rotatable crank members used to drive the cycle.